Geographical and temporal distribution of human giardiasis in Ontario, Canada

BACKGROUND: Giardia is the most frequently identified intestinal parasite in North America. Although information on geographical distribution of giardiasis is critical in identifying communities at high risk, little has been done in this area. Therefore, the objective of this study was to investigate the geographical and temporal distribution of human giardiasis in Ontario in order to identify possible high risk areas and seasons. Two spatial scales of analyses and two disease measures were used with a view to identifying the best of each in assessing geographical patterns of giardiasis in Ontario. Global Moran's I and Moran Local Indicators of Spatial Associations were used to test for evidence of global and local spatial clustering, respectively. RESULTS: There were seasonal patterns with summer peaks and a significant (P < 0.001) decreasing temporal trend. Significant (P < 0.05) global spatial clustering of high rates was observed at the Census Sub-division spatial scale but not at the Census Division scale. The Census Sub-division scale was a better scale of analyses but required spatial empirical Bayesian smoothing of the rates. A number of areas with significant local clustering of giardiasis rates were identified. CONCLUSIONS: The study identified spatial and temporal patterns in giardiasis distribution. This information is important in guiding decisions on disease control strategies. The study also showed that there is benefit in performing spatial analyses at more than one spatial scale to assess geographical patterns in disease distribution and that smoothing of disease rates for mapping in small areas enhances visualization of spatial patterns

Additional file 2: of New var reconstruction algorithm exposes high var sequence diversity in a single geographic location in Mali

Contig pile-ups of the genome of 12 P. falciparum isolates from Mali aligned against the reference 3D7 genome. The genome assembly of each of the 12 isolates, represented by its constituent contigs (blue lines in between blue circles) is aligned against each of the 14 nuclear chromosomes of the reference P. falciparum 3D7 strain (black). The location of var gene sequences is shown (red) in both the 3D7 genome and the contigs aligned to it. (PDF 1608 kb